The major objective of this project, to study the behavior and fate of the roots of transplanted lower vertebrate teeth, continued during the third year of the project. Major emphasis was directed toward animals with a fibrous or hinged type of tooth attachment. The transplanted tooth buds and jaws of the Horned Shark (fibrous attachment) showed little or no growth beyond the covering enamel organ. There was a lack of filling in of the pulpal area and the area of fibrous attachment showed little organization. The anterior chamber proved to be superior to either a subcutaneous or intraperitoneal transplant site. It has not yet been determined whether the lack of growth in the basal plate area is due to inadequate development of the tooth or due to lack of environmental stimulation necessary for the formation of the fibrous attachment. Maintence of small Northern Pike (hinge attachment) proved difficult for long term experiments due to fungus infection: however, the Bullhead and Channel Catfish (hinge-like attachment) were hearty animals and transplants survive and grow to approximately normal size and shape. The autologously transplanted tooth buds and jaw segments of teeth with different types of tooth attachment appear to survive and usually grow.